Plant and mushroom growth medium

ABSTRACT

A growth medium for plants or mushrooms, the medium comprising sugar cane mill mud and non sphagnum-peat material selected from the group consisting of a non-sphagnum peat and coconut fibre.

FIELD OF THE INVENTION

The present invention is directed towards a growth medium for plants.The present invention is also directed towards a growth medium for useas a casing soil in mushroom cultivation.

BACKGROUND ART

In commercial mushroom cultivation it is general practice to provide alower layer of compost which is covered by a layer of a materialreferred to as casing soil. It is important in mushroom cultivation thatthe casing soil assists in maintaining a desirable moisture level formushroom growth. It should also maintain a desirable carbon dioxide andoxygen ratio. Further the casing soil should maintain the nutrientbalance of the compost and also-act as a barrier to disease and insectpests.

To date, the only material which has been recognised by commercialmushroom growers as being acceptable for use as casing material issphagnum peat. Sphagnum peat is partially decomposed sphagnum moss andis obtained from Ireland, Holland and Canada (known as blonde peat).Sphagnum peat has the required ability to retain moisture at levelssuitable for mushroom growth, together with required porosity andnutrient levels.

However, existing sphagnum peat supplies are becoming depleted. Thus,there is a need in the industry for an alternative to sphagnum peat.Still further, the costs of obtaining imported sphagnum peat are highand adds considerably to a mushroom grower's costs. Thus, there is afurther need in the industry for an economically viable alternative tosphagnum peat.

A difficulty with obtaining an alternative to sphagnum peat is that anyalternative must satisfy the particular requirements for mushroomcultivation. As mentioned above, a casing soil must have a moistureholding capacity to ensure that there is sufficient moisture to supportmushroom growth. Other important properties include neutral pH, low saltlevels and suitable nutrient levels. It has been observed that althoughother types of peat such as sedge peat are available they do not satisfythe above requirements and are unsuitable as casing soils. To date,there is no commercially available alternative to sphagnum peat.

In the horticultural industry, it is common practice to prepareartificial growth medium for use as potting mixes. Such growth mediamust have desirable air porosity, water retention properties andsufficient nutrients to sustain plant growth.

Typical commercial potting mixes include a mixture of coarse sand and anorganic material. Such a mixture on its own is generally deficient inmany nutrients necessary for plant growth. Thus, to provide asatisfactory mix, it is necessary to add the nutrients required forplant growth.

Typical organic materials are timber products such as bark chips andcomposted bark material. Although these materials are generally obtainedfrom byproducts of timber production, their supply does rely ondiminishing natural resources.

In an attempt to provide a plant growth medium with desirable propertiesa number of different combinations of materials have been researched.Examples of these earlier studies include the use of filler materialssuch as bagasse, coconut fibre and rice husks with sphagnum peat mossand sphagnum peat.

Filler materials such as bagasse are fibrous materials which contain nosignificant levels of nutrients. Thus, it is necessary to add thenutrient rich sphagnum moss or peat. However, as mentioned above,sphagnum peat is in a finite supply. To date, it is believed there is noacceptable alternative to the use of sphagnum peat in the horticultureor mushroom industries.

It is therefore an object of the present invention to provide a growthmedium for plants and mushrooms which may at least partially overcomethe above disadvantages or provide the public with a useful choice. Itis also an object of the present invention to provide a material for useas a casing soil which may be used as an alternative to sphagnum peat.

SUMMARY OF THE INVENTION

According to a first broad form of the invention there is provided agrowth medium for plants or mushrooms, the medium comprising sugarcanemill mud and a non-sphagnum peat material selected from the groupconsisting of a non-sphagnum peat and coconut fibre.

The growth medium of the present invention may be used in a wide rangeof applications including potting mixes, soil additive, mulch, mushroomcasing soil and also as a top dressing material for germination of grassseeds.

In the present specification and claims, the term “non-sphagnum peat”includes any peat material which is not derived from sphagnum moss. Suchpeat materials include peat derived from sedges or trees. Anothersuitable material is coconut fibre, which is known as coco peat.Typically, coco peat consists of shredded coconut coir (the fibrous partof a coconut shell). The coconut fibre may be either partially compostedor used in its raw state. Combinations of any two or more types of peatand/or coconut fibre may also be used. Sphagnum peat may also beincluded as a minor component of the composition if desired.

The term “sugarcane mill mud” in the present specification and claimsrefers to washing material from sugar cane mills. The washings includecane washings, lime, cane juice impurities and fine bagasse.

Neither non sphagnum-peat materials or sugarcane mill mud when usedexclusively as a plant growth medium or casing soil are suitable forsatisfactory plant or mushroom growth. However, the present inventor hassurprisingly discovered that when a sugarcane mill mud and non-sphagnumpeat are used in combination, a material suitable for use as a plantgrowth medium or casing soil may be obtained.

Neither product on its own is suitable for satisfactorily supportingplant or mushroom growth.

The ratio of non sphagnum-peat material to sugarcane mill mud istypically between about 1.4:1 to about 2:1 parts by weight. Preferablythe ratio is about 1.7:1. The amount may vary depending upon the type ofpeat and source of the sugarcane mill mud. For example, the compositionof the sugar cane mill mud may vary, depending upon the source mill.

Typically, the respective amounts of sugar cane mill mud and nonsphagnum-peat material component are selected so as to optimisedesirable properties such as water retention, aeration, pH, salt contentand nutrient level. For example, non sphagnum-peat materials typicallyhave undesirable properties such as low pH, low nutrient levels and lowair porosity. These properties may be offset by the sugarcane mill mudwhich has near neutral pH, suitable nutrient levels and good airporosity. Conversely, undesirable properties of the sugarcane mill mudsuch as high salt levels, low moisture retention, high levels orsusceptibility to unwanted biological organisms are offset by the nonsphagnum-peat material which was as low salt levels, good moistureretention and is substantially free of nematodes and other soilpathogens.

Preferably, the non sphagnum-peat material sugarcane mill mud are mixedto provide a composition having the ranges as defined in the followingTable 1. TABLE 1 Nutrient Range Air Filled Porosity % 17-25 WaterHolding Capacity % 67-74 pH 6.7-7.2 Electrical Conductivity  0.3-0.45Chloride (ppm) 18-30 Nitrate Nitrogen (ppm) 100-150 Ammonium Nitrogen(ppm) <50 Total Nitrogen (ppm)  60-100 Sulphur (ppm) 25-50 Phosphorus(ppm) 18-40 Potassium (ppm) 16-30 Calcium (ppm) 150-350 Magnesium (ppm)30-60 Sodium (ppm)  5-20 Iron (ppm) 25-50 Copper (ppm) 1.0-4.5 Manganese(ppm) 2-7

When used as a casing soil composition, preferably water is also addedto the peat and/or coconut fibre sugarcane mill mud mixture to provide awater content of between about 65-75% (wt/vol). Typically, the casingsoil composition is sterilised prior to use. Other optional additivesmay also be added. Such additives include wetting agents, fungicides,nematicides, insecticides and texture and pH controlling agents. Suchadditives are known to those skilled in the art. The composition mayalso be supplemented with nutrients, if desired, such that theconcentrations of the respective chemicals fall within the ranges inTable 1.

Where the medium is to be used as a plant growth medium such as pottingmix or top dressing soil, it ma be desirable to add a filler material tomodify porosity and/or water retention. The amount of filler can bevaried, depending upon the desired properties of the mix. This candepend on the type of plant to be grown. Suitably, about 30 to about 80wt % of filler may be added. Potting mixes will typically include about60 to about 70 wt % filler where top dressing soils can contain lowerlevels of filler.

A preferred filler is an inert material. An especially preferred filleris bagasse.

Optionally, further additions known in the art may be added to themedium of the present invention. Such additives include wetting agents,insecticides, nematicides, nutrients and a pH modifying agent.

BEST MODE

By way of Example only, the present invention will be described withreference to the following Examples.

EXAMPLE 1

A 10 tonne batch of casing soil was prepared as follows: Sugarcane millmud having a composition according to Table 2 and sedge peat having acomposition according to Table 3 are sterilised separately at 70° C. for5 hours. 6,250 kg of peat and 3,750 kg of sugarcane mill mud are mixedin a mixer. An effective amount of a pH controlling agent such as gypsumand/or lime is added such that the pH of the mixture is near neutral,typically between about 6.7 to about 7.2. Generally about 100-130 kg ofthe pH controlling agent is added.

A 10 L solution of one or more fungicides is prepared. Preferredfungicides are those available under the trade names Prochloraz andBenomyl. Preferably a 10 L solution of Prochloraz (0.4-0.8 kg) andBenomyl (0.3-0.7 kg) is prepared.

A 10 L solution of an insecticide, nematicide and disinfectant is alsoprepared. A preferred insecticide is available under the trade nameFipronil (0.2-0.4 L), a preferred nematicide is available under thetrade name Fenamiphos (0.1-0.3 L) and a preferred disinfectant isFormalin (1.5-2.25 L).

The moisture level of the mix is measured and the amount of waterrequired to achieve a moisture content of about 75% is calculated.

A wetting agent is then added to the calculated amount of water. Apreferred wetting agent is Alcohol Ethoxylate. Typically about 0.8-1.5 Lof ethoxylate is added to about 0.8-1.0 KL of water.

The sugarcane mill mud and peat are mixed in the mixer at a speed notmore than about 50 rpm for between about 8 to 10 minutes. During mixing,the three aqueous solutions, prepared above, are sprinkled onto themixture. After the solutions have been added, mixing is continued forbetween about 3 to about 5 minutes.

The casing mixture is then ready to be used or packaged. TABLE 2 SEDGEPEAT* Analytical Range at Nutrient/Test Optimum Range different depthAir Filled Porosity % 15-25  2-10 Water Holding Capacity % >40 54-82 pH6.5-7.2 3.6-4.4 Electrical Conductivity 0.2-0.5 0.08-0.12 Chloride 0-100 10-13 Nitrate Nitrogen 100-150 1-2 Ammonium Nitrogen  0-150 0.0Total Nitrogen 150-250 1-2 Sulphur >40 4-8 Phosphorus  8-40 1-2Potassium  35-250 2-4 Calcium  50-340 17-22 Magnesium 25-80 20-24 Sodium 0-70 18-23 Iron 35-70 52-72 Copper 0.4-10  0.04-0.15 Manganese 1.0-15 1-3*The sedge peat is sourced from Butcher's Creek in Atherton. This peatcontains high levels of minerals and a large percentage of undecomposedgrasses, roots and the like which can tie up free nitrogen. Further,this material can break down to a very fine particle size that can clogpore spaces.

TABLE 3 SUGARCANE MILL MUD Nutrient/Test Analytical Range Moisture Level% 67.9-75.5 Water holding capacity % 46.9-62.3 pH 5.8-6.4 Electricalconductivity 0.54-0.77 Total Nitrogen % dm 0.52-0.83 Ammonium Nitrogenppm  5-45 Phosphorus % dm 0.45-0.69 Potassium % dm 0.69-0.89 Calcium %dm 1.01-1.53 Magnesium % dm 0.37-0.43 Sulfur % dm 0.13-0.19

EXAMPLE 2

Example 1 was repeated with the sedge peat being replaced by coco peat.The coco peat has a composition according to Table 4. TABLE 4 COCO PEATAnalytical Range at Nutrient/Test Optimum Range different depth AirFilled Porosity % 15-25 13-18 Water Holding Capacity % >40 63-77 pH6.5-7.2 6.1-6.4 Electrical Conductivity 0.2-0.5 0.29-0.31 Chloride 0-100 59-71 Nitrate Nitrogen 100-150 1-3 Ammonium Nitrogen  0-150 >5Total Nitrogen 150-250   1-3.5 Sulphur >40 2.9-6.3 Phosphorus  8-40 1-6Potassium 35-250 132-166 Calcium 50-340 42-68 Magnesium 25-80 14-23Sodium  0-70 53-57 Iron 35-70 10.1-24.6 Copper 0.4-10    4-7.6 Manganese1.0-15  2.2-7.5

The composition of the casing soil prepared by Examples 1 and 2 has acomposition according to Table 5. This mixture may also be used as aplant growth medium or as a soil additive. TABLE 5 Nutrient Availablelimits of new casing mix Air Filled Porosity % 21-25 Water HoldingCapacity % 70-72 pH 6.8-7.0 Electrical Conductivity 0.375-0.4  Chloride(ppm) 24-28 Nitrate Nitrogen (ppm) 110-125 Ammonium Nitrogen (ppm) 0.0Total Nitrogen (ppm) 75-90 Sulphur (ppm) 30-60 Phosphorus (ppm) 25-35Potassium (ppm) 20-30 Calcium (ppm) 225-300 Magnesium (ppm) 36-45 Sodium(ppm) 14-20 Iron (ppm) 42-45 Copper (ppm) 3.5-4.0 Manganese (ppm) 4-8

The casing soils prepared by Examples 1 and 2 are chemically balancedand ready to use. The texture of the material is able to maintain aratio of carbon dioxide and oxygen which facilitates the initial growthof the mushroom mycelium. (Carbon dioxide is typically generated by thelower compost layer).

The casing soil prepared according to Examples 1 and 2 were observed tohave a high carbon content (which is desirable for optimum vegetativegrowth), a low ash content (about 15 to about 25%), a high level oforganic material (about 540 mg/kg), to be substantially nematode free,substantially free from soil borne pathogens have a moisture content ofbetween about 45 to about 55% and a high moisture holding capacity (ie.a water holding capacity at dry bulb density of 0.4 m/cc at 0.4 msuction is 137% on a dry basis and 55% on a volumetric basis attemperature ranges of 15° C. to 32° C.).

The casing soil was also observed to maintain the moisture holdingcapacity at a minimum level of about 67 to about 72%, to maintain anoptimum level of resistance against unwanted biological organisms duringthe cropping cycle, optimum nutrient levels, a pH of between about 6.7to about 7.2 and also to maintain a desirable texture.

The growth and quality of mushrooms produced using the composition ofthe present invention was compared with the growth and quality ofmushrooms produced using sphagnum peat. The quantity and quality of themushrooms produced using the composition of the present invention wasfound to be comparable to that using sphagnum peat. Comparative tests inwhich sedge peat and sugarcane mill mud were used on their own showedthat the mushroom growth was unsatisfactory.

EXAMPLE 3

A potting mix was prepared by mixing 1.7 parts by weight sedge peat to 1part by weight sugar mill mud. To this mix was added 4 parts by weightbagasse.

EXAMPLE 4

A top dressing material was prepared according to Example 3 except that2 parts by weight bagasse was added. The top dressing material wasspread on a ground surface. Grass seeds were spread on the material atregular intervals. Grass germination and growth was evident over aperiod of about one week. This time was observed to be less than thatwhen using conventional top dressing materials.

The potting mix and top dressing material were also observed to exhibitat least equivalent and generally superior results over conventionalmaterials. However, the medium of the present invention can be preparedusing waste products such as sugar cane mill mud. Thus, the medium canreplace conventional materials currently prepared from limited naturalresources.

It will be appreciated that in the present specification and claims, theterm “comprising” and its derivatives “comprise” and “comprises” willimply the inclusion of the stated integers but not the exclusion of anyfurther integer or integers.

It can be seen that the composition of the present invention provides analternative to conventional sphagnum peat in the production of mushroomsand use as a plant growth medium or soil additive. The compositionenables the production of mushrooms of a quality and quantity comparableto sphagnum peat.

1. A growth medium for plants or mushrooms, the medium comprising sugarcane mill mud and a non sphagnum-peat material selected from the groupconsisting of a non-sphagnum peat and coconut fibre.
 2. The growthmedium of claim 1 wherein the ratio of sugar cane mill mud to nonsphagnum-peat material is between about 1:1.4 to about 1:2 parts byweight.
 3. The growth medium of claim 2, wherein the ratio is about1:1.4.
 4. The growth medium of claim 1 having a composition as definedin Table
 1. 5. The growth medium of claim 1, wherein the nonsphagnum-peat material is a non-sphagnum peat.
 6. The growth medium ofclaim 5, wherein the peat is sedge peat.
 7. The growth medium of claim1, wherein the non sphagnum-peat material is coconut fibre.
 8. Thegrowth medium of claim 1 which is in the form of a casing soilcomposition.
 9. The growth medium of claim 8, which further containsabout 65 to about 75% wt/vol water.
 10. The growth medium of claim 9,which further includes an additive selected from the group comprising afungicide, insecticide, a nematicide, a wetting agent and a pHcontrolling agent.
 11. The growth medium of claim 1, which furtherincludes about 30 to about 80 wt % of an inert filler.
 12. The growthmedium of claim 11, which includes between about 60 to about 70% of aninert filler.
 13. The growth medium of claim 11, wherein the inertfiller is bagasse.
 14. A potting mix comprising about 1.7 parts byweight sedge peat, about 1 part by weight sugar cane mill mud and about4 parts by weight bagasse.
 15. A top dressing material comprising about1.7 parts by weight sedge peat, about 1 part by weight sugar cane millmud and about 2 parts by weight bagasse.
 16. A method of preparing acasing soil composition comprising mixing about 6.25 parts by weightsedge peat or coconut fibre with about 3.75 parts by weight sugar canemill mud, adjusting the pH to between about 6.7 to about 7.2 and addingwater to adjust the moisture content to about 75%.